Muffler



Patented Jan. 15, 1935 UNITED STATES Momma Paul Peik, Chicago, IlL,assignor to The Halsey W. Taylor Company, Warren, Ohio, at corporationof Ohio Application July so, 1932, Serial No. 628,281

6 Claims.

My invention relates to muiilers for silencing the exhaust noise ofinternal combustion en,- gines and other engines periodicallydischarging expanding and noise producing pulsating gases.

The general object 01 my invention is to provide, a short compactmuiiler having a very high degree of silencing or muilling efficiencycombined with a relatively low back pressure.

A further object of my invention is to provide a short compact muiilercapable of efllci'ent scavenging action with reversed flow of theexhaust gases.

A still further object of my invention is to provide a short compactmuflier with reversed flow of the exhaust gases in which the exhaust gasstreams may readily expand and in which oppositely travelling pulsatingexhaust gas streams may partly merge and thus level their shown inFigure 1, the section being taken on line 2-2 of Figure 1;

Figure 3 is a perspective view of the pipe supporting skeleton includingthe solid separating wall between the inlet and outlet pipes of themuiiler;

. Figure 9; and

Figure 11 1s a perspective view of the pipe supporting skeleton of themuiller shown in Figures 9 and having a partly perforated separatingwalLbetween the pipes of the muilier arranged in the compartment formedby said separating wall.

In the form ofmuifier for internal combustion engines shown in Figures 1through 3 of the drawings, an outer preferably cylindrical sheet metalshell 1 is closed at its opposite ends by annular end walls 2, also ofsheet metal. Inner partition walls 3, slightly spaced from end walls 2form narrow spaces 4 at the ends of the cylinder which spaces are filledwith foraminous sound absorbing material 5, such as expanded mica, slagwool, steel wool and the like. These packed sound absorbing spaces arenot absolutely necessary to the proper functioning of the muflier, andtherefore may in most'instances be eliminated.

Mounted within the shell 1 are a series of parallel perforated tubes 6,7 and 8 through which exhaust gas passes in the order named. Aperturedannular sheet metal disks 9 snugly fitted within and adjacent each endof cylinder or shell 1 serve as supports for tubes 6, 7 and 8 and alsoform chambers 10 and 11, between said disks and partition walls 3 forcommunication of tubes 6 and 7 and tubes 7 and 8 respectively to inducereversal of the flow of exhaust gas when passing from one tube into theother. The tube 6, the intake tube, extends with its intake end throughend wall 2' at the intake end of shell 1 for connection with the engineexhaust, not shown, and at its other end into chamber 10 communicatingwith pipe 7; The tube 8 communicates at its inner end with chamber 11and exhausts through end wall 2 at the exhaust end of shell. The tube 7is solely supported by the apertured disks 9 and communicates atopposite ends with the respective chambers 10 and 11. 'Disks 9 arepreferably made from imperforate metal except where provided withaperturesfor tubes 6, '7 and 8. A longitudinally extending separatingwall 12 arranged between the inner wall of shell 1 and tube 7, dividesthe latter into two longitudinal compartment! 14 and 15, each of whichaccommodates one of the tubes 6 and 8. These compartments are packedwith sound absorbing material such as used in the spaces 4, whichmaterial occupies the space around the perforated tubes and completelyfills each compartment.: The separating wall 12 is welded or otherwisesecured at its ends to the disks 9 and at its longitudinal edges to theinner face'or wall of the shell 1 and to the outer face or wall ofperforated tube '7. Preferably the separating wall 12 is of solid sheetmetal for reasons which will be presently explained. That por-- tion ofthe tube 6 which passes through chamber. 11 at the inlet end of shell 1,as W as that part of tube 8 which passes through chamber 10 at theexhaust end .of the shell 1 are solid, that is the perforations formedin the remainder of these tubes are omitted.

Exhaust gases" entering tube 6 flow therethrough into chamber 10 thenceback through tube '7 into chamber 11 and finally into and through tube 8to the open atmosphere. This lQW takes place because the solid wall 12separates the tubes 6 and 8, in which the flow of gas is in the samedirection. The tube '7 in which the flow of gas is in opposite directioncommunicates with tubes 6 and 8 through the perforations of all tubesand the sound absorbing material occupying the space around theperforated tubes.

It is understood that compartments 14 and communicate with each otherthrough perforated tube 7 and that the perforated tubes 6 and 8 arrangedin said compartments communicate indirectly with each other. This is amost important feature of my invention. If the employment of solid wall12 would not permit such communication, it would 'be necessary to makethe diameter of the cylinder or shell 1 much larger in order to makecompartments 14 and 15 large enough for the efficient absorption ofsound in the sound absorbing material packed therein. However, by virtueof the perforated tube 7, which serves as an elongation of theseparating wall 12 separating the inner chamber of shell 1 intocompartments 14 and 15, .the impulses in the gas stream passing throughtubes 6, '7 and 8 are not confined to the compartment housing eachparticular tube, but are free to expand through the perforated tube 7directly into the other housing and its perforated tube in which theflow of gas is in the same direction. Thus impulses in the stream ofexhaust gases flowing through tubes 6 and 8 in the same direction, thatis from the front to the rear of the muflier, are not free to mergedirectly with each other, but only indirectly through tube 7, whereasthe impulses in the stream of gases flowing through tube '7 in adirection opposite to that of the flow through tubes 6 and 8 are free tomerge with the latter and viceversa. This makes it possible for the highimpulses in the gas streams in tubes 6 and 8 to expand through theperforations of their tubes and: ierge with the low impulses of the gasstream in perforated tube '7, and this merging of the high and lowimpulses is continuously taking place throughout the entire muiiler. Asthe gas streamsin tubes 7 and tubes 6, 8 are flowing in oppositedirections the merging action is greatly multiplied and consequently anextremely high degree of mufliing efficiency is attained in spite of thefact that the muiiler is of very short length. As the direction of flowof gases passing through tubes 6 and8 is the same in each of said tubes,and the shearing or merging action previously referred to can not takeplace under .such conditions, separating 1 wall 12 is made solid toseparate these tubes from each other. If wall 12 should be perforated,then the merging eificiency between tubes 6 and 8 would be no greaterthan that of a conventional straight stream acoustic muffler, becausethe mufliing effect attained the short muflier would be insuiiicient toprevent noise with many engines'now on the market, particufrom one tube'through the sound absorbing material into the low pressure area of theex-' seeping passagesbetween their individual gas channels show a verymaterial increase in back pressure, as compared to that of straightstream mufflers of the same capacity. This is due to the fact that theentire stream is twice completely reversed in the former structure. Inmy present invention 1 provide for a progressive transfer of exhaustgases from one compartment to the other compartment, which transfertakes place through a tube in which the, exhaust gas stream travels inopposite direction ascompared with the direction of travel of gas in thetube from which the peaks of the gas stream are expanded. Thistransferaction more than compensates for the increase in back pressure set up bythe two reverses of the gas stream.-

The progressive transfer or merging of im-'-' pulses also results ina'highly efficient scavenging action, as the gases are not trapped inthe -muifler, but are constantly passing along the inner shell from onechamber to the other so that the entire mufiler becomes hot and ismaintained at a temperature above the condensation of water and otherliquids present in the exhaust gas, even in extremely cold weather andunder conditions of intermittent and slow impulses through the elongatedpassage 16 between the inner wall of shell 1 and tube 7'. A materialincrease in the size of this passage .by spacing tube 7' a greaterdistance from the inner wall of shell 1 would decrease the silencingaction of the muflier because a substantial volume of insuiiicientlymerged and muflied gas will enter into tube 8 and thence be exhaustedwith substantial noise. Space 16 should be held to a size which insuressuflicient merging between expanded gas peaks from tube 7 with the V gascreeping and passing through said space 16.

in Figures 6, 7, and 8 which is generally the same as the preferred formof the invention shown in Figures 1 through 3 the perforations of tube7" extend only half circumferentially H around the said tube 7" and atopposite ends of said tube are approximately 180 offset with respect toeach other. Consequently one half of the'length of the tube isperforated for communication with chamber 14.and the other half of thetube is perforated for communication with chamber15, see Figures 7 and8. This arrangement decreases the merging action of the exhaust streamsin tubes '7" and 6 but prevents direct expansion of peaks of the exhaustgas stream from tubes 6 into tube 8. Such inufiler possesses highmufliing efficiency for extremely In the modified form .of the inventionshown short structures but shows a slight increase in back pressure ascompared with the very low back pressure of the previously describedstructures.

The modified form of the invention shown in Figures 9 and 11 shows amufller with a non-perforated intake tube 18 displacing tubes 7 and 7"of the structures shown in the previous figures. The tubes 19 and of themodified form are perforated and arranged in compartments 14' and 15'separated from each other by a separat ing wall 12' similar to thearrangement of wall 12 previously described, with the exception thatwall 12' is perforated throughout approximately half its length. Thedirection of the exhaust gas in tubes 19 and 20 being opposite, thepartly perforated separating wall 12 is provided to permit expansion ofthe peaks of the exhaust gas stream and merging of these streams withsatisfactory muflling action, but the back pressure of this structure isslightly increased as compared with the very low back pressure of thestructures shown in Figures 1 through 5.

Having thus described my invention, what I claim is:

1. In a reverse stream mufller for silencing the exhaust poise ofinternal combustion engines, a shell provided with intake and outletopenings and longitudinally subdivided into parallel compartments,foraminous sound absorbing material in said compartments, a gas passagein each of said compartments, one of said gas passages being incommunication with saidintake opening and another in communication withsaid outlet opening, and a gas passage arranged parallel to,intermediate of and partly within each of said compartments and indirect communication with said other gas passages to provide a singlecontinuous passage through the muffler andthe walls of said passagesbeing foraminous to permit seepage of exhaust gas from these passagesinto said compartments and back into said passages.

2. In a reverse stream mufller for silencing the exhaust noise ofinternal combustion engines, a shell longitudinally subdivided into twoparallel compartments, foraminous sound absorbing material in saidcompartments, a perforated tube in each of said compartments, a tubularextension for one end of each of said perforated tubes, said tubularextensions being extended through the opposite end walls of said shellto provide intake and outlet passages for said muffler, and a thirdperforated tube arranged parallel to, intermediate of and partly withineach of said compartments for indirect communication with saidcompartments and their respective perforated tubes, said thirdperforated tube directly communicating at opposite ends with said twoperforated tubes to provide a continuous unrestricted and reversed gaspassage through said shell.

3. In a reverse stream muiller for silencing the exhaust noise ofinternal combustion engines, a shell provided with intake andoutletpassages and longitudinally subdivided into two parallelcompartments, longitudinally communieating through a narrow space witheach other, foraminous material within said compartments, a perforatedtube longitudinally extending in each of said compartments, one of saidperforated tubes communicating with said intake passage and the otheronewith said outlet passage, and a third preforated tube arrangedparallel to and intermediate said two compartments for communicationwith each of said compartments and their respective gas passages, saidthird perforated tube being in direct communication with said otherperforated tubes to provide a single reversed and unrestricted passagethrough said muflier.

4. In a reverse stream muffler for silencing the exhaust noise ofinternal combustion engines, a shell provided with intake and outletpassages and longitudinally subdivided into parallel compartments by asolid wall, a perforated tube supported upon the upper edge of said walland contacting with the inner wall of said shell, to permitcommunication of said compartments with each other through said tube, aperforated tube longitudinally arranged in each of said compartments andsound absorbing and deadening material packed within said compartmentsand enclosing said tubes, one of said last mentioned tubes being'indirect communication with the intakepassage and the other of saidlastmentioned tubes being in direct communication with said outletpassage, said tubes being in direct communication with saidfirst-mentioned perforated tube to provide an unobstructed reversedsingle gas passage through said shell and permitting expansion of thepeaks of explosion impulses into said compartments and the tubestherein.

5. In a reverse stream muflier for silencing the exhaust noise ofinternal combustion engines, a shell provided with intake and outletopenings and longitudinally subdivided into two parallel compartments,foraminous sound ab sorbing material in said compartments, a gas passagein each of said compartments, one of said gas passages being incommunication with said intake opening and the other one in communication with said outlet opening and a gas passage arranged parallelto, intermediate of and partly within each of said two compartments, thewalls of said passages being foraminous for affording communicationbetween each of said compartmentsand its gas passage, said latter gaspassage being in directcommunication with said other two gas passages toprovide a single continuous and reversed gas passage through the muiilerand the foraminous walls of said passages permitting seeping of exhaustgas from these passages into said compartments. 6. In a reverse streammufller for silencing the exhaust noise of internal combustion engines,a shell provided with intake and outlet passages and longitudinallysubdivided into parallel compartments by a partly perforated wall, atube supported upon the upper edge of said wall and contacting with theinner wall of said shell, a perforated tube longitudinally arranged ineach of said compartments and sound deadening material packed withinsaid compartments and enclosing said perforated tubes therein, said tubesupported in said wall being in direct communication with said inletpassage a'nd one of said perforated tubes, the other one of saidperforated tubes being in direct communication with said last perforatedtube and said outlet passage to provide a single gas passage throughsaid mufiler having the exhaust gas stream flowing through saidperforated tubes in opposite directions and permitting expansion of thepeaks of explosion impulses from one of said perforated tubes into itscompartment and thence through said perforated wall into the othercompartment and its perforated tube.

PAUL G. PEIK.

